Analysis: Yes, another company that doesn't want to be a company. Unlike Wikipedia, though, Mozilla Corp. is already a for-profit corporation--and it's already generating revenue. How much? We estimate about $150 million this year, and close to $100 million in pre-tax profit (you've got to love those open-source labor costs).

Mozilla is another one of these ludicrously high-margin open-source businesses, and it hasn't even begun to tap its revenue potential. Yes, the most vocal of its open-source fans would boycott it if it got any more commercial, but the mainstream market wouldn't. So, when you combine revenue, growth rate, margin, and long-term potential, we find another business that could command a 25X revenue multiple. Throw in some value for Thunderbird, and the whole kit and kaboodle is worth about $4 billion.